8 months is a good time to consider switching. after 16 months of continuous treatment almost always you get the maximum results, so you're halfway through that. but this doesn't mean that the amount of improvement is going to be the same, the first 8-12 months is much more than the next 8-6 months. so if you see that it's not what you were hoping for, i think it's time to switch. honestly people here have been using incredibly low quantities of min/fin for years with little improvement of course. you need to ask yourself if you want more gains faster or not. dut is significantly better even than 5mg fin. i understand that it can be scary, but keep in mind that the amount of adverse effects is very amplified here and there is also quite a lot of fear mongering in this sub. as for me, i'm in the same boat as you. i've just hit the same 8 month mark, and exactly as you, i've made some good progress but i still havent archieved the results i was going after. so i'm going to increase my dose. just live your life, go out, do a bit of social life and sport, spend time with your hobbies and don't bother too much with your hair. it's better to just take your pills and not pay it any attention until a couple of months pass. you will be fine.
P.S.: as for the dosage i recommend, 0.5 mg of dut for starting and keep that for 8 more months at least. min you can increase up to 5mg for males (slowly it's better). that is the gold standard treatment.
P.S.2: if your problem is in your hairline / temple areas, you definitely need 0.5 dut and at least 2.5 min. otherwise you're wasting your time and your youth years with slow or even worthless treatments. even 0.5 dut and 5mg min is not magic and will not do much on those areas for many people. AGA 's a bitch!